2) how good is the warranty - against all types of failure, or what - cedar fences usually fail in one of two ways - tornado/hurricane/waves/flood/car collision takes them out, or the posts (if not treated timber) rot out. The fence itself will change color and get fuzzy as it weathers, but should last 15-20 years in most areas.

3) generally, a fence is not something you would pay for a warranty on - if properly put up and with concreted-in copper chromate or copper napthalate treated posts (the green preservative) should last a long time and not need warranty work basically till the fasteners fail or the fence slat boards split too badly.

4) if I was going to spend extra money on a wood fence, it would be for a good quality penetrating sealer, not steel posts.